#include<bits/stdc++.h>
using namespace std;
int n,k,cnt=-1,number[105];
priority_queue<long long,vector<long long>, greater<long long>> ans;
long long wait=0;
int main()
{
	cin>>n>>k;
	for(int i=1;i<=n;i++)
	cin>>number[i];
	sort(number,number+n+1);
	ans.push(1);
	while(cnt<k)
	{
		while(wait==ans.top())
		ans.pop();
		wait=ans.top();
		ans.pop();
		cnt++;
		if(cnt==k)
		break;
		for(int i=1;i<=n;i++)
		ans.push(wait*number[i]);
	}
	cout<<wait;
	return 0;
}